## STAT 10

(Sec. 3a-3c)

Introduction to Statistical Reasoning

## Instructor: Ivo Dinov, Asst. Prof.

Departments of Statistics & Neurology
 http://www.stat.ucla.edu/~dinov/

Due Date:

# Friday, Oct. 26, 2001, turn in after lecture

See the HW submission rules. On the front page include the following header.

• (HW_4_1) Define the following terms and answer the questions regarding them:
• Parameter
• Estimator
• Estimate
• Bias
• Precision
Can an estimator be unbiased, but imprecise? For the following data what is an unbiased estimator of the population average? Compute the coresponding estimate [sample mean] and its precision [StdError(sample mean)].
 2 5 9 2 3 7 11 2 3 6 4 4 7 6 6 10 4 3 5 7

• (HW_4_2) Compute the correlation coefficient, R(X,Y),  for the following data. Please do this by hand and show all of your work.
•  X Y 1 0 3 1 5 4 7 7 9 8

• (HW_4_3) Find the equiation of the line, l1,  passing through the points (-3, 5) and (X=1, Y=2). Identify the slope, m1,  and Y-intercept, b1,  of the line. A line, l2, is perpendicular to l1 if its slope is -1/m1. Can you find the equation of the line, l2, perpendicular to l1, which goes through the point (X=0, Y=3). What are l2's slope, m2, and Y-intercept, b2?

\Ivo D. Dinov, Ph.D., Departments of Statistics and Neurology, UCLA School of Medicine/